The invention relates broadly to a tool for recovering magnetic objects from an earth cavern. More specifically, the invention provides an electromagnet tool particularly adapted for recovering magnetic objects from earth caverns filled with liquids.
There are several commercially available tools in which permanent magnets or electromagnets are used to retrieve magnetic objects from underground holes, such as bore holes for oil or gas wells. Most of these tools are designed for picking up drilling rig parts, such as drill bits, which come loose or break off during drilling operations and drop to the bottom of the bore hole. Since the object to be retrieved is lodged in the bore hole itself, the magnetic tool can be lowered in a direct line, that is, through the well casing, until it makes contact with the object. In some underground operations, however, tools or other metallic objects may be lost in a cavern, such as a brine well cavern. If the object in the cavern should be in a position which is not in a direct line with the well casing, it can be extremely difficult or impossible to maneuver the magnetic tool into a position where it can make contact with the lost object.
Another drawback of many of the conventional magnetic tools is that the magnet surface area is small, or the shape of the magnet surface may be such that the tool will pick up only specific objects, such as a drill bit. The tool of the present invention overcomes most of the problems described above. For example, the pickup surface of the electromagnet used in the present tool is designed such that it will attach to magnetic objects of various shapes and sizes. In addition, the present tool may be equipped with various guide means which enable it to maneuver in a cavern until it locates the lost object.